Measuring instrument



Dec. 10, 1940. G. D. WEBBER MEASURING INSTRUMENT Filed March 28, 1938 2Sheets-Sheet 1 ffim ATTORNEYS 10, 1940. WEBBER 2,224,281

MEASURING INSTRUMENT Filed Mal-Ch 28, 1958 2 Sheets-Sheet 2 INVENTOR.65025.? 2 14 5555 AfioRNEYs UNITED STATES PATENT OFFICE MEASURINGINSTRUMENT George D. Webber, Cleveland, Ohio, assignor m Webber MetricGage Company, Cleveland, Ohio,

a corporation of Ohio Application March 28, 1938, Serial No. 198,414

14 Claims.

This invention relates to an improvement in precision measuringinstruments, for instance, an instrument adapted to ascertain dimensionsof articles of manufacture which are required to be made within closetolerances. The invention is especially adapted for use in mechanicaland optical comparators, and cer ain of the embodiments disclosed can beused effectively as dial gages on machine tools.

An object is to provide an inexpensive support for an indicator or alight reflector or transmitter (optical lever part) by which angularmovement of the indicator or lever part is confined to one plane,without interference with free movement of the support in such plane.

Another object is to provide a pivotal support and operating means foran indicator table, on which the table will be free to movesubstantially in one plane only, but which will permit the instrumentemploying the table to be operated in any position.

A specific object is to provide an improved mechanical comparator.

Another specific object is to provide a measuring instrument in whichmeasurements are displayed through the agency of an optical lever orcombination of optical levers.

Other objects and features of the invention will become apparent fromthe following description relating to the accompanying drawings, showingthe preferred forms. The essential charac eristics are summarized in theclaims.

Referring briefly to the drawings, Fig. 1 isa perspective view, showinga measuring instrument unit arranged for use e. g. in a mechanicalcomparator or dial gage; Fig. 2 is a longitudinal central sectional viewthereof as indicated by the line 2-2 on Fig. 1; Fig. 3 is an enlargedfragmentary side elevation of an indicator table or beam and asupporting and stabilizing arrangement for i Fig. 4 is a fragmentarydetail plan view showing one side of the table and a modified form ofstabilizer; Fig. 5 is a plan view of another modified form ofstabilizer; Fig. 6 is a diagrammatic view showing a modified pivotalsupthe same type as the measuring mechanism unit shown in myapplication, Serial No. 164,171, filed September 16, 1937, and may havea dial housing (not shown) carrying a scale 2 traversed by an indicatorarm 3 supported on a head or frame 4 which may be of generallycylindrical form as shown, so that it may be clamped in any turnedposition adjacent a machine tool for centering or measuring (as a dialgage) or in an operating standard including a work support for use as acomparator with e. g. gage blocks to set it for a series of measuringoperations. The unit may have a movable feeler pin 5 adapted to contactwith work to be measured or tested or with such gage blocks as usual.The controlling or actuating means including the feeler and some of theparts operated by it, could be replaced by means enabling e. g. weight,fiow, temperature, etc., measuring operations to be effected.

The cylindrical frame I may comprise a top piece 8 and a bottom piece Iof suitable metal, the two slidably supporting thefeeler 5 in suitablebores as shown in Fig. 2. The feeler 5 actuates or controls the positionof a table or beam ill which in this specific form is the short arm of amechanical lever, the indicator 3 being the long arm. The indicator maybe made of light wire with leg portions l2 inserted in openings ornotches in the table and fastened as by solder. The indicator swingsparallel with the scale out of contact therewith but close thereto foreasy reading.

A counterweight for the indicator "arm is shown as a loop of wire 3asecured to the table, as on the opposite side thereof from the indicatorand dependiiig therefrom; having a weight piece 32) in proper positionto counter-balance the indicator. This device permits the instrument tobe used effectively in any position as for dial gage work in centeringrotating bodies or measuring distances at any angle to vertical orhorizontal planes. The weight piece can depend directly below theindicator and comprise extensions of its legs.

Referring further to Figs. 1 to 3, the table or beam i comprises, asshown, a fiat, rectangular piece of metal. carefully finished on itsbottom side (and at least one edge for point locations). The table restson a fixed fulcrum, shown as two spherical surfaces, each of which has asingle point contact with the plate. The spherical surfaces may beafforded by calibrated steel ballsii of the type used for bearings. Aslight distance away from the vertical plane of the two i tut-(merely ofthe table), the plate rests on a movable support also shown as a ballII, which is connected with the feeler I in such manner that uponmovement of the feeler by the work. the table II is tilted on the ballsll. Knife edges or cone points or circular discs can be used instead ofthe spherical supports. The ball supports are much simpler to make, thanknife edges or points, and wear on the balls in the course of isinsignificant. "Calibrated ball bearings of "extreme accuracy can now bepurchased as standard parts and are easy to mount either fixedly, as theballs II, or on a moving part as in the case of the ball ll. NoV-notches are required in the construction," thereby greatlysimplifyingeaccurate manufacture of the table orbeamvIOH'ItisaImost'impossible to form the apex of a V-notch in a singlepiece of metal, without aslight fillet. t 7 As the table is tilted, thesurface thereof moves in contact with (rocks around the axes of) theballs I! and It; and while. actually (assuming the, balls cannot rotate)the surface must slide either on .the'ball III or onboth II jand I! whenthe table tilts from horizontal posij tiong'the movement of theindicator'is found very j steady in actual practice. The table canbeheld in contact with the spherical supports by gravity or suitablesprings to be later described.

' The ball ll may befsecured as by a spinning I operation in acomplementary socket centrally ofjthe top end of a sliding pin 20, whichis guided in aligned bores 2l and 22 in upper and lower the bottom pieceI of the frame. Upward move- 21, andjthetable In is tilted to a degreedeterment of the pin may be limited as by the head of a screw 26' belowthe piece 1 or in any other way" so thatthe plate ill will: not belifted out of engagement withits fixed fulcrum. The connection betweenthefeeler l and pin III is impositive so that the feeler'icannotdamagethe working parts if raised too high under a considerable force. Thefeeler 5, aspreviously mentioned, is slidably mounted in the upper andlower pieces 6 and I in the same manneras the pin fl and, within thehollow interior of theframe, the feeler has a disc member 21 overhanginga portion of the collar 25 at oneside so that relative upward movementof the feelerpin allows the spring ll to cause the pin to follow thefeeler. Up-. ward movement ofthe feeler pin is resisted by a a spring30, which is of the necessary strength to produce the desired pressureof the feeler pin on the work. In any event, the spring II exerts aconsiderably greater force than 'the'spring 24, in order thatthe feelerpin cannot be moved by the spring 2|. When the feeler pin is movedtoward the frame 4 by the work, the spring it maintains contact betweenthe members" and pin 5.

In order that the abutment relationship between the disc members 2! and21 of the pin 2| mined by the amount of movement of the feeler I andfeeler I will not be changed during use of the instrument by relativeturning of the disc members, turning ofboth the pin and feeler beprevented by cross pins and II inslots of the pin II and feelerrespectively. 7

To maintain the table in contact with both sets of spherical supports(II and It). I may provide tension springs it which occupy slots a inthe 5 frame piece The springs may be anchored to Y the frame as on pinsll extending into the slots. At theirupperendsthespringsmaybeloopedtoembrace} reduced shank portions 36 of pins 31 extending laterally fromthe table. As suggested 10 in Fig. 4. the pins 81 may be pressed intosuitable aligned bores in the opposite sides of the table between thesupporting planes of the two sets of balls. The pins 31 have disc-likeheads 38 which effectively to anchor stabilizer links to be u; laterdescribed. The springs 32 are very-light;

.cit being necessary that their effective strength shall not-be-greaterthan that of the spring 24 on the ball supporting pin 20, in anyposition of the table. 2o

Adjustment between the fixed I and movable balls. is usually necessaryin order tochange the throw of the indicator 3 with reference to thescale for calibration, is accomplished by sliding a 7 plate 40 which:supports the balls l5. Such ad- 25 justment need never be disturbedafter original setting. The ballsll are fixed .to the plate 40 "as incupsfor cupped'posts, as desired, and the plateau be guided for movementnormal to the supporting planes of the two sets of balls by reason ofdepending ribs It in parallel guide channels 42. There is an enlargedopening 40' through which the pin 20 carrying the ball II passes, sothatthe plate may be moved back and forth'in changing the length of theshort arm or the lever (distance between ball centers).

The plate ll is usually adjusted initially by a special temporaryfixture having micrometric movement. However, as shown. there are screwsI in'blocks M set into the top piece 6 of the 40 framerthe screws havingtheir ends adapted for engaging opposite ends of the plate. Foranchoring the plate, after adjustment, I preferably use a screw ll whichenters the frame from the bottom, has a head ll relatively underlyingthe frame, and is threaded as 'at 41 into the lower side of the plate40. The receiving bore or bores for the clamp screw II in the frame mayhave a few thousandths of an" inch clearance so as to permit thenecessary lateral movement ofthe clamp screw.

One stabilizing arrangement for holding the table l0, particularlyagainst rotational displacement on the supports it and lt'butwhichconmotion will not interfere with the necessary free tilting movement ofthe table, comprises the provision of ,a set of links 5| between thetable and part of its support, such, for instance, as an upstandingbracket II at one end'of the adjustable plate '0. The links are soassociated with the table that the table is operatively engaged by thelinks in such manner as to fixthe rocking center of the table, on thecenters of the balls II. The heads "of the pins 31 may be madesufficiently large in diameter to extend past the rocking center, and bymeasuring from a finished face such a as II of the plate II anddownwardly from the P nch them to form small cone bearing subp rt- 'ingsockets. I! for the outer ends of the links. The sides of the bracket llare similarly prick- Dunched at the same elevation. The links which maybe light spring-tempered sheet metal strips, can have conical points Ipimched on them as 7 indicated in Fig. 4; and may be held with thepoints seated in the conical sockeis by a single pring Ii bearing onboth links in line with their points 54. The apex angle of the pointsis, of course, slightly less than the angle of the prickpunchings fortrue poin bearing contact between the strips and the table bracket.

The links cause the table to around the fixed ball centers and while thebottom surface of the table must slide on the balls I, in thearrangement shown, the fixed pivots or points of attachment of the linksmay be located approximately on the center of an are which nearlycoincides with the curve of the sockets 52 in case the plate simplyrolls on the balls II but does not slide.

Since the rocking center of the plate I. does not shift with respect tothe plate ll in the operationoftheinstrument,thelinks,asshownin Fig. 5,may be made as a single U-shaped piece 81oiwireorsheetmetalhavingspringarms" with hearing points I! adapted to beseated in the conicalsocketsoftheheadslloranyother part of the table bythe spring of the arms toward the table. The base portion of the memberI is secured to an upward projection II of the plate 4. as illustratedin Fig. 5; leaving free base portions of the U at each side of theprojection for slight spring effect if needed.

In an instrument that is designed always to be operatedin uprightposition (see Figs. 9 and the construction can be simplified by omittingthe pins 81 for the hold-down springs .32, together with such springsand so arranging the stabilizer arms a that their points 591: engageprick-punchings directly in the sides of the table which are shown asdropped below the finished surface of the table which rests on the fixedand movable supports l5 and it. The points 59a can be located betweenthe vertical transverse planes of engagement of such bottom surface withthe ball supports l5 and I6 so that the stabilizer can function as ahold-down spring by reason of the torsional spring of the freecross-portions of the attached base 510 of the stabilizer.

Fig. 6 illustrates an economical construction that may be used insteadof the spherical supports for the table it. Posts 65 and the upperportion 66 of a pin corresponding to the pin 20 may be finished at theends with oppositely beveled surfaces as indicated; each providing asingle point contact with the table as on the axes a. and a. In suchcase the links 5. or 58 would be secured to the table at the axis a, inline with the lower pin-contacting surface of the table.

All of the above described principles can be utilized in measuringinstruments, irrespective of the type of measurement desired, forinstance, space, weight, temperature, flow, etc; and irrespective of howthe table II operates to convey or transmit the desired information. Twoadaptations for transmitting the tilting motion of the table or beam byoptical means are shown in Figs. 7 to 10. The novel features of theoptical instrumentalities will be claimed in a copending application.

The stabilizing means for the beam or table (I04 and lb in therespective modification of Figs. '7 and 9) can be somewhat simplified inthe employment of the mechanism hereof with optical instrumentalities,principally because the distance between the fixed support of the tableand the point of contact of the actuator therewith can, in many cases,be as much as .150", whereas in the case of use as a mechanicalcomparator or dial gage where the length of the indicator arm is limitedby weight and deflection factors, said distance should be considerablyless, say in the neighborhood of .010".

As shown in Pig. '1, the table or beam Ila. has a flat bottom surface incontact with spherical supports II and It, as previously described. Thestabilizer arms It may be connected both to the table and to thesupporting plate a by cap screws ll, having reduced cylindrical shankportions I2 between the heads and threads a few thousandths of an inchlonger than the thickness of the links Ill, so as not to bind the links.The links have openings which nicely fit the cylindrical shanks 12 butso as not to restrain free movement on the supporting balls. The screwsare in line with the axis of generation of the spherical supports it,both horizontally and vertically, and in order to provide supports forthe screws below the smooth bottom face of the table or beam Ila, thetable may have downward extensions formed as-integral parts of the tableor separate pieces as at I3. The extensionpieces It may carry pins ll(shown on their inner sides) for hold-down springs 320, or suchhold-down springs can be secured to the heads of the screws H by makingthe heads wide enough to support spring attachment pins in a regionbetween the transverse vertical planes of the spherical supports. Thiswould be substantially the reverse of the arrangement described inconnection with Figs. 1 to 4, for the hold-down springs and stabilizinglinks and needs no illustration. The above construction of stabilizinglinkage does not require any spring connection between the links to holdthe links in operating position.

Referring to the optical system as shown in Fig. '1, this comprises a,light-source 80, a transparent or translucent scale Bl extendinglengthwise of the table (1. e. parallel to its tiltingmovement), theimage of which scale is projected by the light-source onto a reflector82, mounted in diagonal position at one edge of the table Illa andadjacent its top face as in suitable retaining notches. This may reflectthe image directly onto a distant screen, but in order to condense theoptical elements into a relatively small space, while obtainingconsiderable eflective optical lever length, the reflector 82 isarranged to pro- Ject the scale image onto a transparent reflectingprism 84, having angularly disposed reflecting (back) surfaces 85 andlit, for imposing the scale image onto a reflector 81 mounted on thetable adjacent the reflector 82 or comprising merely a lateral extensionof it. The reflector 81 may impose the scale image on another reflectoror mirror 88, appropriately mounted as in a suitable housing above thereflector 81 for transmission of the image as by a project 31' onto asuitablescreen or, alternatively, into a telescope 9., having aneyepiece and index mark (not shown) for observation in convenientrelationship to a measuring feeler member of a comparator for distancemeasurement.

The importance of the stabilizer arms in the optical arrangement justdescribed will readily be apparent since rotational movement of thetable Illa on its spherical supports could move the image of the scaleout of the range of vision of the operator using such telescope or, asdue to unsteadiness, result in an inaccurate reading. The previousarrangements employing ball supports or substantially their operativeequivalent had always I believe, reflector surfaces (cf. 82) parallelwith the surface of the table which engaged the supports. With such entrotational movement (skewing) of the table would not be disadvantageousbecause it would reflect the image imposed on it in one turnedpositionthe same as in another.

ably supported in fixed position in the housing,

onto a reflector 03 disposed up ht on the top surface of the table ilbwhich rests on relatively flxed and movable tilting supports such asballs I and It. In this case, as in the optical arrangement of Fig. 7,shifting ofv the table ilb on its spherical supports (in the plane ofthe table) would displace the image horizontally out of properrelationship to the telescope (if used) or to a screen such as shown,(described below). I The reflector 03 may transmit the scale imagebackthroughthelens l2 toa reflectingprism OI disposed closely beside thescale in fixed podtion and with its front face parallel to the scale.The prism in turn transmits the image through a magnifyin eyepiece itwhich is appropriately arranged to focus the image on a screen It (e. 8.ground glass) with an index mark on it, as indicated at 91. Thisarrangement is preferred to the Fig. '7 arrangement for a shopcomparator, because it presents the scale image in more convenientposition for observation byranoperator while adjusting the work incontact with a'feeler. with the tilting centers of the table supports I5 and I6 spaced .050" and with the lens II arranged for a magnifyingratio of 1 to 5 the measuring -feeler movement and scale image movementratio (in one design) is.001 to l. i

The uses of the various forms of the invention shown are not limited-todirect reading, as by sight. For illustration, I contemplatemodification of the indicating means controlled by the tilting table orbeam It, "a, llb, etc., for the operation of a stylus on a moving recordstrip, or the affixing of an image on such strip photographically, aswith optical systems such as shown or modiflcations thereof. In makingsuch record, (say of continued measuring operations such as grinding orthe continuous checking of .metal strip thickness) stronger springs canbe used to tilt the table or beam in one direction so that the recordcan be made mechanically as by a stylus on material which placesconsiderable work on the table or beam in moving the stylus thereover.

I claim: a

1. In a measuring instrument having a beam with substantially coplanarsurface portions which are in pivotal contact respectively-withrelatively fixed and movable members, the latter of which tilts the beamon the flxed member, arm members connected with the beam on'oppositesides of it generally in the region of its tilting axis, said membersextending away from said axis, in the direction of extent of thelongitudinal axis of the beam; remote portions of the arms beinganchored whereby to prevent rotation of thebeam, in a plane parallel tosaid surface portions.

2. In a measuring instrument having a beam with substantially coplanarsurface portions in pivotal contact with relatively flxed and movablemembers, the latter of which tilts the beam, and means pivotallyconnected with the beam on opposite sides of it substantially at itstilting thebeam.

means comprising links extending in thedireci tion of the length of thebeam and additional yielding'meansccnnectedtothebeamandacb ing thereonin a direction normal to the flat surface, both said means connectingthe beam and the frame whereby to prevent rotation of the a relativelyflat surfacein its' own plane on the fulcrum.

4. In a measuring instrument, a motion translating beam or table havingcoplanar surface portions in pivotal contact with fixed and movablesupports, the latter being an actuator for tilting the beam about theflxed support, and wherein the contact between the beam or table and thesupport is such that the beam or table could normally float parallel tosaid coplanar surface portions; a "pair of arm members extending in adirection generally parallel withsaid surface and having cone and socketconnections with the beam and means to support the remote :5 ends of thearms whereby to stabilize the beam against movement in a plane parallelto said 'surface.

.5. A measuring instrument according to claim 4 wherein thecone-and-socket bearing contacts I are substantially at the tilting axisof the beam 49 and are yieldingly maintained.

6. A measuring instrument according to claim 4, wherein the arms areconnected together by a spring in a manner to impose uniform pressure atboth cone and socket connections.

7. A measuring instrument according to'claim 4, wherein the pivotalconnections of the arms and beam lie in a plane between that of thetilting axis and the axis of the movable support, and the arms arearranged yieldingly to urge the relatively flat surface ofthe'beam'toward its pivotal supports.

8. In a measuring instrument, a'motion translating beam in pivotalcontact with fixed and movable supports, thelatter being an actuator fortilting the beam, a U-shaped resilient member having points at its endspivotally engaging conicalsocketsinthebeamorpartsofitinthe generalregion of the tilting axis of the beam, and means connecting the baseportion of the U-shaped member with a fixed part of the instrument, nearone end of the beam so as to stabilise a 9. In a measuring instrument, amotion tramas lating beam having a relatively flat surface in one side,pivotal supports for the beam in contact with said surface fordetermining the tilting axis of the beam, a movable actuator adjacentsaid axis andarranged to move toward and 70 awayfrom thebeamtotiltit,pinsextenrlingin oppomte directions from the beam with their axesin a plane between the tilting axis and the axis of movement of theactuator, springs connected to the pin coaxially therewith and addi- 7itionally to fixed portions of the instrument for holding the fiatsurface in contact with the pivotal supports, heads on the pins whichextend laterally therefrom beyond the tilting axis, and stabilizer meansin addition to the springs and connected with said heads substantiallyat said tilting axis and additionally connected to fixed portions of theinstrument, said means preventing skewing movement of the fiat surfaceon the pivotal supports.

10. In a measuring instrument, a beam having a relatively flat surface,relatively fixed and movable members both in pivotal contact with thesurface, one adapted to be'displaced by the work to be measured, meanson the beam including a surface adapted to divert or transmit a lightbeam for optically projecting the movement of the beam which lattersurface extends at an angle to the relatively fiat surface of the beam,and stabilizing link members pivotally connected to the side edges ofthe beam and additionally connected to fixed portions of the instrumentin a manner to preventdisplacement of the relatively flat surface in itsown plane on the relatively fixed and movable members.

11. In a measuring instrument, a beam adapted and arranged to be tiltedfor displaying or transmitting a measurement, said beam having arelatively fiat surface, relatively fixed and movable pivotal supportsfor the beam. whereby it may be tilted, one of said supports comprisinga cylindrical pin which has a planar diagonal face atitsendsoastoformwithonecircularsidesurface an acute angle, the apex ofwhich contacts with such fiat surface of thebeam.

12. In a measuring instrument having a beam adapted to transmitinformation to a remote point, a rocking support for the beam includingfixed and movable members in contact with the beam, a guide for themovable member, means for stressing the movable member toward the beam,a feeler pin and a guide for it generally parallel to the movablemember, one-way-acting abutments between the member and fecler, a springacting on the feeler in a direction opposite the direction of action ofthe stressing means and tending to hold the abutments in contact witheach other, said spring having greater efiective force than thestressing means, and the feeler pin being movable, in a direction tostress the spring, a distance greater than the movable member can bemoved toward the beam.

13. In a precision measuring instrument of the type having a frame and alever element with substantially coplanar surface portions in pivotalcontact respectively with a relatively fixed member and a relativelymovable member, and in which the lever element would normally be free tofioat in a plane parallel to the coplanar surface portions; stabilizingmeans pivotally connected with the lever element closely adjacent oneregion of pivotal contact aforesaid and connected tothe frame in aregion remote from the aforesaid region of connection lengthwise of thelever element, whereby to prevent such floating movement of the leverelement.

14. In a precision measuring instrument of the type having a frame, alever element adapted for transmitting motion with reference to a scale,an actuator element movable in a direction to swing the lever element,and a fulcrum element in close proximity to the actuator element andabout which the lever element swings, and in which the surface contactbetween the lever element and said other elements is afforded wholly byspherically surfaced members bearing on fiat surfaces so that the leverelement would normally be free to float in a direction parallel to thefiat surfaces;

the improvement comprising spherical surfaces on the lever elementformed about a common axis directed transversely of the lever element,the latter spherical surfaces being located beside the beamiii-reference to the plane in which the lever element swings andapproximately in transverse alignment with the region of spherical andflat surface contact aforesaid, and means connected to the frame andhaving portions bearing on said latter spherical surfaces "of the leverelement in opposite directions lengthwise of the lever element forpreventing such floating movement.

. GEORGE D. WEBBER.

